The present invention relates to an image processing method and an image processing device which are capable of separating a background area of an image.
In recent years, a visual communication apparatus with a camera has begun to come into wide use. For example, a system for a television conference which a plurality of persons join is known in the field of business, while a communication system which utilizes a Web camera is known in the personal field. In such systems, a display image of the other party is displayed on a display device, and an image of a user who visually observes the screen of the display device is captured as an image of a photographing object. The resulting image signal is transmitted to an image processing device on the other party side through a network including a public line, a dedicated line or the like, whereby it becomes possible to make both the users have the realistic sensations.
However, a problem common to those systems is such that information on an area other than a person is desired not to be transmitted to the other party. The present system with which all the information on an image captured with a camera is transmitted to the other party involves such a limitation that the system must be installed in a place an image of which may be shown to the other party.
Then, a method is expected in which an image part of a person (foreground) and an image part of a background are separated from each other, the image part of the background is subjected to some processing or other, and so forth.
That is, a foreground area containing an image of moving objects such as a user is cut down from a moving image which is captured in a camera system, and the cut-down image of the moving objects is subjected to predetermined processing, whereby robust image processing becomes possible which is hardly influenced by the feature of the background. In addition, when information on the background is desired not to be sent to the other party, the foreground and the background are separated from each other and only information on the foreground is delivered, thereby realizing the robust image processing.
Here, as regards a method of separating a background and a foreground from each other, for example, there is known a method in which a person area is specified by using a heat sensor, and a background area is subjected to predetermined image processing (see Patent document 1 for example), a method in which a movement area is detected based on a background difference, an interframe difference, and a stereo method to be made a foreground (see Patent document 2 for example), a method in which a distance region is specified and information on an image falling within the distance region is outputted (see Patent document 3 for example), or the like.
Patent document 1:
Japanese Patent Laid-open No. Hei 9-200714
Patent document 2:
Japanese Patent Laid-open No. 2000-20722
Patent document 3:
Japanese Patent Laid-open No. 2000-200359